﻿#include "md5.hpp"

#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

//share structure
// global structure template


#define SWAP(n) (n)
#define BLOCKSIZE 4096
#define rol(x,n) ( ((x) << (n)) | ((x) >> (32-(n))) )
//
//void md5_process_block( const void *buffer, size_t len, struct md5_ctx *ctx );
//
//static void md5_process_bytes( const void *buffer, size_t len, struct md5_ctx *ctx );
static int md5_stream ( FILE *stream, void *resblock );

static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };

static char md5str[64];
static unsigned char bin_result[16];
//最外层
static int process( FILE *stream )
{
    //char md5str[33] = { 0 };
    md5_stream( stream, bin_result );
    int i;
    for( i=0; i<16; i++ ){
        sprintf( md5str+i*2, "%02x", bin_result[i] );
    }
}

///////////////////////////////////////////////
void md5_init_ctx ( struct md5_ctx *ctx )
{
    ctx->A = 0x67452301;
    ctx->B = 0xefcdab89;
    ctx->C = 0x98badcfe;
    ctx->D = 0x10325476;
    ctx->total[0] = ctx->total[1] = 0;
    ctx->buflen = 0;
}

static void* md5_read_ctx ( const struct md5_ctx *ctx, void *resbuf )
{
    //
    ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
    ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
    ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
    ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
    return resbuf;
}

void* md5_finish_ctx ( struct md5_ctx *ctx, void *resbuf )
{
    //md5_ctx
    /* Take yet unprocessed bytes into account.  */
    md5_uint32 bytes = ctx->buflen;
    size_t pad;
    /* Now count remaining bytes.  */
    ctx->total[0] += bytes;
    if (ctx->total[0] < bytes)
        ++ctx->total[1];
    //
    pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
    memcpy ( &ctx->buffer[bytes], fillbuf, pad );
    /* Put the 64-bit file length in *bits* at the end of the buffer.  */
    *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP ( ctx->total[0] << 3 );
    *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ( (ctx->total[1] << 3 ) | (ctx->total[0] >> 29));
    /* Process last bytes.  */
    // md5_process_block
    md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
    // md5_read_ctx
    return md5_read_ctx (ctx, resbuf);
}

//最外层第二
static int md5_stream ( FILE *stream, void *resblock )
{
    struct md5_ctx ctx;
    char buffer[BLOCKSIZE + 72];
    size_t sum;
    /* Initialize the computation context.  */
    md5_init_ctx (&ctx);
    /* Iterate over full file contents.  */
    while (true)
    {
        /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
        computation function processes the whole buffer so that with the
        next round of the loop another block can be read.  */
        size_t n;
        sum = 0;
        /* Read block.  Take care for partial reads.  */
        while (true)
        {
            //
            n = fread ( buffer + sum, 1, BLOCKSIZE - sum, stream );
            sum += n;
            if (sum == BLOCKSIZE)
                break;
            if (n == 0)
            {
                /* Check for the error flag IFF N == 0, so that we don't
                exit the loop after a partial read due to e.g., EAGAIN
                or EWOULDBLOCK.  */
                if ( ferror (stream) )
                    return 1;
                goto process_partial_block;
            }
            /* We've read at least one byte, so ignore errors.  But always
            check for EOF, since feof may be true even though N > 0.
            Otherwise, we could end up calling fread after EOF.  */
            if ( feof (stream) )
                goto process_partial_block;
        }
        /* Process buffer with BLOCKSIZE bytes.  Note that
        BLOCKSIZE % 64 == 0
        */
        //求一整块数据的md5
        md5_process_block ( buffer, BLOCKSIZE, &ctx );
        //post it to scp
    }
process_partial_block:;
    /* Process any remaining bytes.  */
    if (sum > 0)
        md5_process_bytes (buffer, sum, &ctx);
    /* Construct result in desired memory.  */
    md5_finish_ctx ( &ctx, resblock );
    return 0;
}

/* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
result is always in little endian byte order, so that a byte-wise
output yields to the wanted ASCII representation of the message
digest.  */
//单一的，零散的函数，非计算文件md5之需要函数
void* md5_buffer ( const char *buffer, size_t len, void *resblock )
{
    struct md5_ctx ctx;
    /* Initialize the computation context.  */
    md5_init_ctx (&ctx);
    /* Process whole buffer but last len % 64 bytes.  */
    md5_process_bytes (buffer, len, &ctx);
    /* Put result in desired memory area.  */
    return md5_finish_ctx (&ctx, resblock);
}

#define UNALIGNED_P(p) (((md5_uintptr) p) % sizeof (md5_uint32) != 0)

//此函数调用md5_process_block，核心算法　md5_process_block
void md5_process_bytes ( const void *buffer, size_t len, struct md5_ctx *ctx )
{
    /* When we already have some bits in our internal buffer concatenate
    both inputs first.  */
    if (ctx->buflen != 0)
    {
        size_t left_over = ctx->buflen;
        size_t add = 128 - left_over > len ? len : 128 - left_over;
        memcpy ( &ctx->buffer[left_over], buffer, add );
        ctx->buflen += add;
        if (ctx->buflen > 64)
        {
            md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
            ctx->buflen &= 63;
            /* The regions in the following copy operation cannot overlap.  */
            memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
                ctx->buflen);
        }
        buffer = (const char *) buffer + add;
        len -= add;
    }
    /* Process available complete blocks.  */
    if (len >= 64)
    {
        // *buffer = void
        //
        long ptr = (long)buffer;
        //
        if( ptr%sizeof(int)!=0 )
        //if (UNALIGNED_P (buffer))
            while (len > 64)
            {
                md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
                buffer = (const char *) buffer + 64;
                len -= 64;
            }
        else
        {
            md5_process_block (buffer, len & ~63, ctx);
            buffer = (const char *) buffer + (len & ~63);
            len &= 63;
        }
    }
    /* Move remaining bytes in internal buffer.  */
    if (len > 0)
    {
        size_t left_over = ctx->buflen;
        memcpy (&ctx->buffer[left_over], buffer, len);
        left_over += len;
        if (left_over >= 64)
        {
            md5_process_block (ctx->buffer, 64, ctx);
            left_over -= 64;
            memcpy (ctx->buffer, &ctx->buffer[64], left_over);
        }
        ctx->buflen = left_over;
    }
}

/* These are the four functions used in the four steps of the MD5 algorithm
and defined in the RFC 1321.  The first function is a little bit optimized
(as found in Colin Plumbs public domain implementation).  */
/* #define FF(b, c, d) ((b & c) | (~b & d)) */
#define FF(b, c, d) (d ^ (b & (c ^ d)))
#define FG(b, c, d) FF (d, b, c)
#define FH(b, c, d) (b ^ c ^ d)
#define FI(b, c, d) (c ^ (b | ~d))
/* Process LEN bytes of BUFFER, accumulating context into CTX.
It is assumed that LEN % 64 == 0.  */
void md5_process_block (	const void *buffer, size_t len, struct md5_ctx *ctx )
{
    md5_uint32 correct_words[16];
    const md5_uint32 *words = (unsigned int*)buffer;
    size_t nwords = len / sizeof (md5_uint32);
    const md5_uint32 *endp = words + nwords;
    md5_uint32 A = ctx->A;
    md5_uint32 B = ctx->B;
    md5_uint32 C = ctx->C;
    md5_uint32 D = ctx->D;
    /* First increment the byte count.  RFC 1321 specifies the possible
    length of the file up to 2^64 bits.  Here we only compute the
    number of bytes.  Do a double word increment.  */
    ctx->total[0] += len;
    if (ctx->total[0] < len)
        ++ctx->total[1];
    /* Process all bytes in the buffer with 64 bytes in each round of
    the loop.  */
    while (words < endp)
    {
        md5_uint32 *cwp = correct_words;
        md5_uint32 A_save = A;
        md5_uint32 B_save = B;
        md5_uint32 C_save = C;
        md5_uint32 D_save = D;
        /* First round: using the given function, the context and a constant
        the next context is computed.  Because the algorithms processing
        unit is a 32-bit word and it is determined to work on words in
        little endian byte order we perhaps have to change the byte order
        before the computation.  To reduce the work for the next steps
        we store the swapped words in the array CORRECT_WORDS.  */
#define OP(a, b, c, d, s, T)						\
    do								\
        {								\
        a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;		\
        ++words;							\
        a = rol (a, s);						\
        a += b;							\
        }								\
        while (0)
        /* Before we start, one word to the strange constants.
        They are defined in RFC 1321 as
        T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64, or
        perl -e 'foreach(1..64){printf "0x%08x\n", int (4294967296 * abs (sin $_))}'
        */
        /* Round 1.  */
        OP (A, B, C, D,  7, 0xd76aa478);
        OP (D, A, B, C, 12, 0xe8c7b756);
        OP (C, D, A, B, 17, 0x242070db);
        OP (B, C, D, A, 22, 0xc1bdceee);
        OP (A, B, C, D,  7, 0xf57c0faf);
        OP (D, A, B, C, 12, 0x4787c62a);
        OP (C, D, A, B, 17, 0xa8304613);
        OP (B, C, D, A, 22, 0xfd469501);
        OP (A, B, C, D,  7, 0x698098d8);
        OP (D, A, B, C, 12, 0x8b44f7af);
        OP (C, D, A, B, 17, 0xffff5bb1);
        OP (B, C, D, A, 22, 0x895cd7be);
        OP (A, B, C, D,  7, 0x6b901122);
        OP (D, A, B, C, 12, 0xfd987193);
        OP (C, D, A, B, 17, 0xa679438e);
        OP (B, C, D, A, 22, 0x49b40821);
        /* For the second to fourth round we have the possibly swapped words
        in CORRECT_WORDS.  Redefine the macro to take an additional first
        argument specifying the function to use.  */
#undef OP
#define OP(f, a, b, c, d, k, s, T)					\
    do 								\
        {								\
        a += f (b, c, d) + correct_words[k] + T;			\
        a = rol (a, s);						\
        a += b;							\
        }								\
        while (0)
        /* Round 2.  */
        OP (FG, A, B, C, D,  1,  5, 0xf61e2562);
        OP (FG, D, A, B, C,  6,  9, 0xc040b340);
        OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
        OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);
        OP (FG, A, B, C, D,  5,  5, 0xd62f105d);
        OP (FG, D, A, B, C, 10,  9, 0x02441453);
        OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
        OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);
        OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);
        OP (FG, D, A, B, C, 14,  9, 0xc33707d6);
        OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);
        OP (FG, B, C, D, A,  8, 20, 0x455a14ed);
        OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);
        OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);
        OP (FG, C, D, A, B,  7, 14, 0x676f02d9);
        OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
        /* Round 3.  */
        OP (FH, A, B, C, D,  5,  4, 0xfffa3942);
        OP (FH, D, A, B, C,  8, 11, 0x8771f681);
        OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
        OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
        OP (FH, A, B, C, D,  1,  4, 0xa4beea44);
        OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);
        OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);
        OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
        OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);
        OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);
        OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);
        OP (FH, B, C, D, A,  6, 23, 0x04881d05);
        OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);
        OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
        OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
        OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);
        /* Round 4.  */
        OP (FI, A, B, C, D,  0,  6, 0xf4292244);
        OP (FI, D, A, B, C,  7, 10, 0x432aff97);
        OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
        OP (FI, B, C, D, A,  5, 21, 0xfc93a039);
        OP (FI, A, B, C, D, 12,  6, 0x655b59c3);
        OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);
        OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
        OP (FI, B, C, D, A,  1, 21, 0x85845dd1);
        OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);
        OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
        OP (FI, C, D, A, B,  6, 15, 0xa3014314);
        OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
        OP (FI, A, B, C, D,  4,  6, 0xf7537e82);
        OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
        OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);
        OP (FI, B, C, D, A,  9, 21, 0xeb86d391);
        /* Add the starting values of the context.  */
        A += A_save;
        B += B_save;
        C += C_save;
        D += D_save;
    }
    /* Put checksum in context given as argument.  */
    ctx->A = A;
    ctx->B = B;
    ctx->C = C;
    ctx->D = D;
}

int MD5::computerFileMD5(  const char* path, char* md5sum )
{
    FILE *stream = fopen( path, "r" );
    if( stream==0 ){
        return -1;
    }
    md5_stream( stream, bin_result );
    int i;
    for( i=0; i<16; i++ ){
        sprintf( md5str+i*2, "%02x", bin_result[i] );
    }
    fclose(stream);
    strcpy( md5sum, md5str );
    return 0;
}

int MD5::computerStrMD5( const char* str, char* md5sum )
{
    //
    md5_buffer( str, strlen(str), bin_result );
    int i;
    for( i=0; i<16; i++ ){
        sprintf( md5str+i*2, "%02x", bin_result[i] );
    }
    strcpy( md5sum, md5str );
    return 0;
}

void MD5::demo1()
{
    //QString md5 = MD5::computerMD5( QFileInfo(ui->lineEdit_3->text()));
}

void MD5::demo2()
{
	char md5sum[32];
    int result = computerStrMD5( "abc" , md5sum );
}


//static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };

/**
 *
 * **/
int sumFile ( FILE *stream, char* md5str  )
{
    unsigned char bin_result[16];
    int retVal = md5_stream ( stream, bin_result );
    if ( retVal == 0 ) {
        for ( int i = 0; i < 16; i++ ) {
            sprintf ( md5str + i * 2, "%02x", bin_result[i] );
        }
    } else {
        fprintf ( stderr, "error md5!" );
        return -1;
    }
    return 0;
}

/***
 *
 * **/
int sumBuf (  const char* buf, char* md5str )
{
    unsigned char bin_result[16];
    md5_buffer ( buf, strlen ( buf ) /***/, bin_result );
    for ( int i = 0; i < 16; i++ ) {
        sprintf ( md5str + i * 2, "%02x", bin_result[i] );
    }
    return 0;
}
